Hi
Do you need the longer car wing mirrors when towing the Troll 550??

The actual legal requirement for extended wing mirrors is a bit vague and open to interpretation by the local police.
Being risk averse I fit mirrors anyway to my Triton 430 even though I don't need or use them as such.
Your Troll is wider than my Triton and I would imagine that you would need them anyway.

I use Milenco Aero, not the cheapest but possibly the best for stability and ease of attachment.

I always use them on my triton. Keeps the police uninterested, and reminds me I'm towing a caravan.

There's no point in not fitting extension mirrors when towing, whatever the size of van/car. As others say, it reduces the risk of being pulled over and delayed and gives you a better view of the van AND the road behind it. Why bother not fitting them?

We have the Milenco aero 2, which some would have thought would be an overkill on our 320, but I won’t tow without extra mirrors.
Just changed to Troll 540 and Milenco’S perfect.

EMUK mirrors are really good, very steady and basically can’t be lost like Milenco’s
See here Towing mirrors

Looking at the diagram on the Milenco mirrors box reinforces the need not to use extension mirrors. My Troll 540 is exactly (to within a millimetre) the same width as the bodywork of my Volvo XC60 (excluding the Volvo’s mirrors). They are both 200cm wide.

As such I satisfy the conditions for the required view without towing mirrors so surely they are unnecessary.

The point is to be able to see more behind the caravan than you can with ordinary mirrors even if the mirrors happen to be as wide as the van. Fitting mirrors to your Volvo will give a much wider angle as you'll be viewing from further away from the car body. However if you want to get pulled over and argue the toss with the police and maybe get a ticket and a delay, go ahead. It's much, much easier to take the precautionary approach and avoid such things in the first place. A sound principle for all safe motoring.

If my mirrors show the required view in the diagram above I can’t see the point of fitting extension mirrors. Otherwise extension mirror should be used even when not towing as they undoubtedly give the driver a better view.

What's the point of not fitting them and giving the police a reason for pulling you over and at the least delaying your journey.

I do agree that it's down to individual choice.

I was just trying to ascertain whether I'd gain any advantage in terms of my rear view or if it was simply a case of warding off unwarranted attention from traffic police. I'm loathe to buy extra kit if I don't really need it.

Well you could try marking out the required 4m at 20m distance and see if you really can see the required amount.